Not all "all in one" printers have fax capabilities. Many all in ones have many functions such as copy, print, scan, and fax. However, a few models lack the capability to send faxes.
They are not as reliable as regular printers. The new all-in-one printers incorporate nowadays a scanner, a copier, a fax and a printer and some models even an incorporated telephone handset.
The price of an all in one printer has dropped dramatically in recent years. An ink jet printer can be purchased for less than fifty dollars at a local Walmart or Target.
Some of the good brands that offer all in one printers include cannon which costs about $100. Another option HP officejet or the HP photosmart which even includes fax.